Fitness: Fight back against Alzheimer's with exercise

Montreal Gazette

2 days ago

It's never too early to lower the risk of Alzheimer's, which is a neurodegenerative disease characterized by memory loss and cognitive decline, and accounts for 60-80 per cent of dementia cases. With no cure in sight, the immediate focus is on prevention and delaying the disease's progression.
Most preventative efforts centre around lifestyle changes relating to several modifiable risk factors, including diabetes, high blood pressure, obesity, smoking and inactivity. And since physical activity has an effect on all these risk factors, it's considered an important element in the fight against Alzheimer's, with studies reporting regular exercise reduces the risk of the disease by as much as 45 per cent.
Exercise has long been associated with better mental acuity, largely because of the increase in blood flow to the brain. So even those who show no signs of memory deficit can experience a cognitive boost from a bout of exercise, though its effects largely dissipate within an hour or two post workout. As welcoming as those results are, it's the effects of years of regular exercise that can really make it a difference when it comes to Alzheimer's prevention.
Habitual exercisers demonstrate less brain atrophy when compared with their sedentary age-matched peers, especially in the regions of the brain linked to learning and memory. As we age, brain volume naturally decreases as does blood flow to the brain, so any intervention that mitigates its shrinking and improves circulation through all areas of the brain potentially reduces memory loss. This is especially important during midlife when many of the neurological changes associated with Alzheimer's begin. Several studies have shown active older adults have more stable cerebral blood flow compared with their less active peers.
But like most studies on the effect of exercise on health, information about the type, intensity and volume of exercise it takes to realize any benefits are the next logical steps in learning more about its efficacy. Yet, as the progression from when the disease first begins developing, to symptoms and then diagnosis can take decades, studying the effect of exercise on Alzheimer's isn't easy — or quick. But there are brain markers that signal physiological changes related to Alzheimer's and tests of cognitive performance that can suggest a predisposition to the disease, both of which can be used when testing the effect of exercise on brain health.
Hoping to shed more light on Alzheimer's prevention and treatment, a team of researchers from the department of Kinesiology at the University of North Carolina analyzed the latest studies exploring the effect aerobic exercise and strength training have on brain function and structure.
Much of the research on the effects exercise has on memory and brain health has focused on aerobic exercise, largely because of its ability to increase the delivery of oxygenated blood to the brain. A five-month exercise intervention reported significant improvements in cognitive skills and working memory in a group of older adults who went swimming twice a week when compared with those who participated in a stretching program. Similar results have been reported in adults already showing signs of memory loss, which suggests even in those already exhibiting symptoms of cognitive decline, aerobic exercise can offer marked improvement.
The benefits of cardio on brain health have also been validated by sophisticated imaging. MRIs (magnetic resonance imaging) performed on 59 sedentary older adults assigned to an aerobic exercise group showed significant increases in brain volume (gray and white mass and hippocampal volume), which researchers suggest is enough to protect against 'one or two years of age-related atrophy.'
'These findings suggest that aerobic exercise preserves memory-related structures and maintains brain health and cognitive resilience in aging populations,' the researchers said.
But it's not just cardio that increases brain function. Weight training, particularly workouts that build lower body strength, has also shown positive improvements in working memory and brain structures.
As for exercise intensity and volume, workouts need to be at a moderate to high intensity and performed several times a week for brain function to improve. There's also some evidence physical activity that demands decision making (like sports) and/or a social element offers additional benefits.
Interestingly, not all improvements to memory happen immediately post exercise. Studies that used extended follow-ups noted some results showed up only after 12 months of regular exercise.
The propensity of evidence on the positive effects exercise has on the brain makes its role in brain health indisputable. But don't wait until you notice memory lapses to gear up your exercise routine. Given Alzheimer's can begin developing as early as 20 years prior to the onset of symptoms, the protective effects of exercise can be reaped well in advance of your golden years. Think of every workout as insurance against memory loss and the progressive decline in brain size that occurs with aging.
'Given the recognition that preclinical changes occur decades prior to the diagnosis of Alzheimer's disease and the lack of effective pharmacological treatments to prevent Alzheimer's disease, early intervention through lifestyle behaviours may be critical for preventing Alzheimer's disease in the growing population of older adults,' the researchers said.